EP0792441B1 - Self-calibrating open-channel flowmeter - Google Patents
Self-calibrating open-channel flowmeter Download PDFInfo
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- EP0792441B1 EP0792441B1 EP96928890A EP96928890A EP0792441B1 EP 0792441 B1 EP0792441 B1 EP 0792441B1 EP 96928890 A EP96928890 A EP 96928890A EP 96928890 A EP96928890 A EP 96928890A EP 0792441 B1 EP0792441 B1 EP 0792441B1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/002—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow wherein the flow is in an open channel
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
- G01F1/58—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects by electromagnetic flowmeters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/14—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measurement of pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/284—Electromagnetic waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/284—Electromagnetic waves
- G01F23/292—Light, e.g. infrared or ultraviolet
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/296—Acoustic waves
- G01F23/2962—Measuring transit time of reflected waves
Definitions
- the subject invention relates to a self-calibrating open-channel flowmeter including means for determining the flow coefficient for a particular site by examining the sensed velocity of the flowing fluid versus the level at one or more flow rates. The flow coefficient is then used to convert local velocity to average velocity over a wide range of fluid levels at that site.
- both the level and velocity must be measured accurately because both parameters vary as flow varies in such a piping system under open channel flow conditions.
- the slope and roughness of the pipe control the relationship between velocity and level.
- the slope (or grade) of the pipe chosen for a particular site is the result of civil engineering considerations determined by such factors as the terrain, whereas the roughness factor is the result of the surface of the pipe and obstructions such as bends and elbows.
- This technique utilizes the continuity equation which states that the flow Q is equal to the product of the mean (average) velocity V and the area A of the partially filled pipe, both which are measured at a common cross-section.
- Instruments using the velocity/area technique typically cannot directly measure the average velocity accurately enough for commercial use, and hence they typically contain a modifier that acts on the sensed velocity (local velocity) to better approximate the average velocity. This is true when the sensed velocities are localized to the bottom of the conduit, the sensed velocity is at the surface itself, on any other location that is not a direct measure of the mean velocity.
- the slope and roughness of the pipe establishes a velocity and level relationship under open channel flow conditions.
- the velocities tend to be higher for a given level and roughness, and as the roughness of the pipe increases the velocity tends to be lower for a given slope and level.
- the relationship between velocity and level are controlled by the slope and roughness of the pipe and the pipe diameter. Because it is very difficult to measure the actual average velocity directly, a variety of techniques have been developed where local velocity is measured (i.e., a sensed velocity that is related but not equal to the average velocity), and then the local velocity is modified so as to provide an accurate estimate of average velocity.
- the local velocity is measured near the bottom of the pipe.
- An appropriate modifier is determined by profiling the site with a portable velocity meter or by other means where the average velocity is determined at one or more flow rates, and subsequently through empirical equations contained in computer software the sensed velocity is transformed to an accurate approximation of the average velocity V over a wide range of levels (i.e. flow rates).
- DE 40 16 529 C1 discloses a fluid flow measuring device for open channels comprising a fluid velocity sensor and a liquid level or depth sensor for measuring the velocity of the fluid flow within the open channel and for measuring the fluid level, respectively.
- the velocity sensor can be moved over the whole cross-section of the open channel by positioning means so that a velocity profile can be obtained by measuring the fluid flow velocity at different points of the cross-section thereof. After obtaining a velocity profile a cross-sectional averaged velocity can be calculated so that it is possible to determine a coefficient for determining the cross-sectionally averaged fluid flow velocity from a sensed velocity measured at a referenced position within the open channel.
- the cross-sectionally averaged flow velocity depends on the liquid level or depth and since the coefficient for calculating the cross-sectionally averaged flow velocity from the sensed velocity at a given reference position also depends on the liquid level or depth, it is possible to determine the averaged flow velocity and the corresponding reference position for sensing the actual velocity of the fluid flow within the channel for different water levels and to store the respective coefficient in a memory to avoid calibrating the fluid flow measuring apparatus in each case that the liquid level has changed.
- such a self-calibrating device or process is capable of reacting to various conditions that could result from downstream blockages or from tidal effects. Such conditions could cause the water level to rise and the velocity to slow down creating a different velocity/level relationship for that period of time where the unusual condition exists. Separating these data sets obtained from this changed condition allows for different coefficient to be applied to each of the sets of different flow regimes.
- the object of the present invention is to eliminate the necessity of independent site profiling.
- the present invention provides an improved flow meter, in which any local velocity measurement - be it near the bottom, at the surface, or anywhere in-between and utilizing different velocity sensing means - electromagnetic, acoustic, microwave, optical or other is modified so as to cause it to better approximate the cross-sectional average or mean velocity.
- the modifying means utilizes velocity/level relationships for any particular velocity measuring techniques that have been gathered under controlled conditions and in comparison to local site characteristics provides information to determine what the multiplier factor relating the sensed velocity to the average velocity should be for a particular location (site). This multiplier factor (or flow coefficient) could vary with other parameters such as depth.
- the present invention further provides a self-calibrating flowmeter having a default flow coefficient.
- the self-calibrating flowmeter may be installed with the default flow coefficient, and once exposed to flow, the measured level and velocity data obtained on site is compared to a library of data stored in the memory to arrive at an improved flow coefficient using data stored in a computer or archived in tabular form.
- Figs. 1, 3 and 5 illustrate how the family of profile curves varies with pipe characteristics.
- Fig. 1 represents a pipe with low slope/high roughness
- Fig. 3 a pipe with moderate slope/moderate roughness
- Fig. 5 represents a pipe with high slope/low roughness.
- Figs. 2, 4 and 6 are tables of graph values accompanying Figs. 1, 3 and 5, respectively, wherein 1 means the fluid level or depth, V means the cross-sectional average of the velocity, V S means the sensed velociy, and k means V /V S .
- a low slope/high roughness pipe will exhibit lower velocities throughout the profile for a given depth of flow than a high slope/low roughness pipe will.
- the velocity at 7 inches above the channel bottom is 6ft/s because the pipe is steeper or smoother or both.
- Various combinations of pipe slope and roughness are found in most open channel piping systems.
- FIG. 7 the relationship between pipe characteristics and scatter plot characteristics of the conduit conditions of Figs. 1, 3 and 5 are shown for corresponding electromagnetic velocity sensor locations one inch off the channel bottom, which corresponds to a typical location for an electromagnetic sensor positioned to measure a sensed local velocity in a sanitary sewer without collecting debris.
- FIG. 7 depicting sensed velocity vs. depth.
- Fig. 7 demonstrates that the characteristics of a scatter plot (such as slope and offset) are related to the characteristics of the pipe (pipe slope, roughness) where a level/velocity sensor is installed.
- the scatter plot for the profiles in Fig. 1 depicts a smaller change in velocity for an incremental change in level ( ⁇ V/ ⁇ L) than the scatter plot of the profiles of Fig. 5 which have a greater velocity change for the same incremental change in level.
- This behavior is directly related to the nature of the family of profile curves, which, in turn, is directly related to the characteristics of the pipe size/slope/roughness etc.).
- Other characteristics of the scatter plot provide additional (but less dramatic) insight into the site characteristics, the curvature of a best fit curve through the scatter plot being one such characteristic.
- the pipe characteristics that influence scatter plot shapes also influence which flow coefficient is required to convert the sensed velocity (as measured by a level/velocity meter) to the average velocity. More particularly, the velocity multipliers (average velocity divided by sensed velocity) for the profile curves given in Figs., 1, 3 and 5 have been plotted versus the flow depth.
- the velocity multipliers average velocity divided by sensed velocity
- a single "flow coefficient" to define a particular set of velocity multiplier values for various depths of flow.
- the pipe represented in Fig. 1 requires a flow coefficient to 1.5, while the Fig. 3 profiles require a flow coefficient of 1.35, while the Fig. 5 profiles require a flow coefficient of 1.2.
- the reason for the difference in flow coefficient is that the slope/roughness differences in the pipe affect velocity profile shapes. By examining the velocity/level scatter plot characteristics the flow coefficient can be surmised at a particular site because it is directly related to the pipe slope/roughness as well.
- a portable flowmeter installation includes a flowmeter 2 installed inside a manhole 4 so as to measure the flow velocity of liquid 6 in a conduit 8.
- Manholes are normally installed where there is a change in direction, slope, or pipe size, or otherwise where there is a need to have access to the flow.
- Figs. 10-13 illustrate various examples of different sensors for measuring the velocity of liquid flow in a conduit.
- Velocity sensors are generally of the electromagnetic, acoustic Doppler, microwave doppler, laser Doppler, correlation or scintillation type.
- Level transducers normally include bubbler type pressure transducers, submerged pressure transducers, submerged acoustic level transducers, and look-down acoustic, laser or microwave level transducers.
- Fig. 10 shows an electromagnetic velocity sensor 10 mounted on the bottom of conduit 1. Such bottom-mounted transducers are often secured in place by mounting bands (not shown). This electromagnetic velocity sensor also contains in the same housing a submerged pressure transducer 12. These combinations of velocity and level transducers are connected to the electronic processing contained in flowmeter 2 unit via cable means 14.
- Fig. 11 illustrates a bottom-mounted Doppler velocity sensor 16 and a submerged pressure transducer 18. Again a cable 20 connects the sensors to the electronic processing unit.
- Fig. 12 shows a bottom-mounted Doppler surface velocity sensor 22 and a submerged pressure transducer 24. Again cable 26 connects the sensor to the flowmeter electronic processing means.
- Fig. 13 illustrates a look-down velocity sensor 28 and a look-down depth sensor 13 connected by cable 32 to the electronic processing module.
- the signal processing of the depth and velocity signals includes the improved processing means of the present invention.
- the outputs of depth sensor 46 and velocity sensor 48 are converted by signal processors 50 and 52 to the site depth signal Ds and the site velocity signal Vs, respectively.
- signal processors 50 and 52 By use of the microprocessor 54 with RAM memory, corresponding depth and velocity signals are stored as pairs of data.
- ROM memory means 56 contained in the more permanent read-only (ROM) memory means 56 are previously obtained pairs of velocity and level data that have been collected under controlled conditions in either a flow laboratory or in a carefully conducted field test. Data sets have been obtained for all pipe sizes expected to be seen by the device in the field under various slope and roughness combinations. Also contained in memory 56 are site flow coefficients that correspond to the level dependent multiplier and which serve to convert the sensed velocity to mean velocity once the particular flow condition at the field has been recognized.
- comparison means 58 which includes a microprocessor that compares data contained in RAM 54 (particularly the site velocity V S and the depth velocity D S ).
- the pipe size signal P S from manual source 53 is supplied to comparison means 58 via encoder 57.
- comparison means 58 searches in memory means 56 to find an equivalent velocity/level relationship for the particular pipe size and that particular velocity measuring device (i.e., bottom-mounted electromagnetic, bottom-mounted Doppler, surface-mounted velocity sensor, and the like). For each type of velocity measuring device there must be stored the reference velocity and levels and corresponding site calibration coefficient C F . Once the corresponding curves have been matched, then the corresponding site calibration coefficient C F (which is generally depth dependent) is supplied to the site velocity modifying means 62 together with the depth signal D S .
- the site calibration coefficient C F and the depth signal D S are supplied to the site velocity modifying means 62, whereupon the depth-modified coefficient C F ' is supplied to first multiplier means 64 together with the sensed velocity V S , thereby to produce the average velocity signal V which is supplied as one input to third multiplier means 66.
- To the other input of the third multiplier means 66 is applied an area signal A S which is the product of pipe size signal P S produced by second multiplier means 67 from manually-set pipe size signal generator 53 and pipe size encoder 57, and the site depth signal D S .
- the desired flow signal Q S is produced at the output of the third multiplier means 66.
- a means of collecting these various relationships is achieved.
- inputs to a data acquisition memory consist of five different inputs (i.e., the average velocity obtained from the reference standard, the sensor type, the sensed velocity, the sensed depth, and the pipe size corresponding to each of the previous inputs).
- the data is run on each pipe size, or on a range of pipe sizes, and are recorded on a ROM.
- the reference depth and reference velocity and the ratio R of average velocity to reference velocity at each depth are recorded in the ROM along with the corresponding pipe size and sensor type by means of which the measurements were obtained.
- the processing of the site depth signal D S and the site velocity signal V S are processed together with pipe size signal P S , and the sensor type signal produced by manually-set sensor type signal generator means 59 and sensor type encoder 61. These signals are processed by microprocessor 54 and a corresponding RAM (Randon Access Memory) and ROM.
- the local sensed velocity and depth signals are digitized and stored in RAM 54 along with information regarding the pipe size and the sensor type for that particular site.
- Inputted to the comparison means 58 is the sensed velocity, sensed depth, pipe size, conduit size and sensor type information.
- the comparison means searches the ROM 56 so as to find that stored data that is pertinent for this sensor type.
- the next step is that from the stored data for the sensor type the stored data corresponding to the site conduit size is located. From the stored information pertinent to both the pipe size and the sensor type, the V S and D S of the site is compared to the V R and D R in the appropriate memory section so as to find the best fit V R and D R that match the data pair V S and D S . For each matching pair of data points, the corresponding flow coefficient C F is chosen and subsequently provided to the site velocity modifying means for multiplying by the sensed local velocity V S .
- the average velocity, the level and the subsequent flow rates can either be stored for later use, or be channeled to an indicator for instant read out.
- the set of stored relationships in memory 56, 156 can be a computer program that compares the velocity/level data that is recorded over some period of time, or just one velocity/level part itself so as to provide the correction factor.
- the stored general relationship of memory 56, 156 which have been theoretically or experimentally derived, are compared with the local velocity and depth relationship at any particular site so as to determine a correction factor that which is tailored to that site so as to modify the sense velocity to be actually an approximation of average velocity under those site conditions.
- Fig. 17 An alternate means of modifying the sensed velocity utilizing velocity/level relationships is indicated in Fig. 17.
- the depth signal D S is divided by the site velocity signal V S via division module 153 producing at its output the ratio Ds Vs.
- the level/velocity relationship represents the level/velocity at a particular flow condition.
- Comparison means 158 is a microprocessor that combines this ratio of depth to velocity D S /V S and the depth D S and pipe size P S to search for an equivalent pair of reference ratios DR/VR. Once the set of reference ratios have been found in memory 156, the calibration coefficient C F for this particular site condition is processed similar to that of Fig. 14.
- a velocity/level flowmeter Because of expense, quite often users do not wish to install a velocity/level flowmeter at all sites. In particular a "level only" type flowmeter will work as long as the velocity and level relationship are stable and repeatable for a particular site. In such cases the user may use a weir or flume which have predictable level-to-flow rate relationships or alternatively, by performing extensive site profiling to determine the level-to-flow rate relationship of a standard piece of conduit under various flow conditions, and if such conditions are stable one can utilize this information to obtain flow from just a level reading itself. However, such site profiling at different levels (flow rates) is both time consuming and possibly dangerous due to confined space entry conditions. The present invention lends itself to provide a much easier and more accurate means of establishing the level to flow relationship in a standard conduit.
- the flow rate Q S1 at a particular site has been obtained by the instant invention and stored along with the depth D S1 at the site for each flow rate.
- pairs of data points Qs 1 and Ds 1 that were measured with the instant invention are stored in an electrical erasable prom EEPROM 260.
- the information in this EEPROM can either be copied electrically, or the EEPROM physically removed and installed in a second flowmeter.
- This second flowmeter does not have a velocity sensor but only has a level or depth sensor.
- the depth sensor does not necessarily need to be of the same type as was used to collect the original depth and flow rate data.
- This depth signal D S2 is analyzed by a microprocessor in this level-only flowmeter. For every depth signal D S2 , the memory means 260 is searched for an equivalent depth signal D S1 , and once this is found, the flow corresponding to D S1 is read out of memory 260 and is outputted as Q S2 .
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Description
Claims (15)
- Fluid velocity measuring apparatus for indicating the cross-sectional average rate of fluid flow in an open-channel conduit, comprising:(a) sensor means (46, 48) for producing local depth (DS) and local velocity (VS) signals at a given open-channel site, the local depth signals correspond to the local depth of the fluid in said conduit;(b) first multiplier means (64) for multiplying said local velocity signal and a flow coefficient (CF), thereby to produce a cross-section average velocity signal (
V ); characterized by(c) memory means (56) for storing a plurality of sets of reference depth (DR) and reference velocity (VR) signals previously gathered under controlled conditions in either a flow laboratory or in a carefully conducted field test, the reference depth (DR) signal corresponding to the depth of the fluid in said conduit, each set corresponds to one of a plurality of flow coefficients (CF), respectively, each of which is representative of the ratio between cross-sectional average velocity (V ) to sensed velocity (VS); and(d) comparison means (58) arranged to compare said local depth (DS) and local velocity (VS) signals with said reference depth (DR) and reference velocity (VR) signals, and to select the corresponding flow coefficient (CF), respectively, in reaction to various conduit conditions. - Apparatus as defined in claim 1, wherein said flow coefficients (CF) correspond with different conduit sizes and cross-sectional configurations, respectively.
- Apparatus as defined in claim 1, wherein said flow coefficients (CF) correspond with different velocity sensor types.
- Apparatus as defined in claim 1, wherein said flow coefficient (CF) depends on the local depth of the fluid in said conduit; and further including modifying means (62) for producing a distinctive flow coefficient (CF') depending on said local depth signal, said distinctive flow coefficient (CF') is supplied to said first multiplier means (64).
- Apparatus as defined in claim 4, wherein said comparison means (56) is responsive to the size and cross-sectional configuration of the conduit, and means (53, 57) for supplying to said comparison means (56) a conduit size signal (PS) indicating the conduit size and configuration.
- Apparatus as defined in claim 5, and further including second multiplying means (67) responsive to said conduit size signal (PS) and to said local depth signal (DS) for producing an area signal (AS) indicating the cross-sectional area of the fluid flow within the conduit, and third multiplier means (66) responsive to said average velocity signal and to said area signal for producing and output flow signal (QS) indicating the rate of fluid flow in said open-channel conduit.
- Apparatus as defined in claim 1 wherein said comparison means (158) compares the ratio of said local depth and local velocity signals produced by divider means (153) with reference ratios of a plurality of sets of reference ratios for selecting the corresponding flow coefficient (CF).
- Apparatus as defined in claim 1, wherein said sensor means comprises an electromagnetic sensor as velocity sensor and further wherein said memory means contains sets of depth and velocity reference signals representative of those produced under controlled conditions by electromagnetic sensor means.
- Apparatus as defined in claim 1 wherein said sensor means comprises a submerged Doppler signal generator; and further wherein said memory means contains sets of depth and velocity reference signals representative of those produced under controlled conditions by submerged Doppler signal generator means.
- Apparatus as defined in claim 1 wherein said sensor means is selected from the group consisting of submerged acoustic time-off travel velocity sensing means, acoustic look-down velocity sensing means, microwave look-down velocity sensing means, and look-down optical sensing means; and further wherein said memory means contains sets of depth and velocity reference signals representative of those produced under controlled conditions by said velocity signal sources, respectively.
- A method for measuring the cross-sectional average rate of fluid flow in an open channel conduit, comprising:(a) previously generating under controlled conditions in either a flow laboratory or in a carefully conducted field test a plurality of sets of reference depth (DR), the reference depth (DR) signal corresponding to the depth of the fluid in said conduit, and reference velocity (VR) signals each set corresponds to one of a plurality of flow coefficients (CF) respectively, each of which is representative of the ratio between cross-sectional average velocity (
V ) to sensed velocity (VS),(b) storing said respective sets of reference depth (DR) and reference velocity (VR) signals and said corresponding flow coefficients (CF) in a memory means;(c) supplying sensed depth (DS) and velocity (VS) signals to a comparison means and comparing said local depth (DS) and local velocity (VS) signals with said reference depth (DR) and reference velocity (VR) signals to select a corresponding flow coefficient (CF) from said memory means in reaction to various conduit conditions, the sensed depth (DS) signals correspond to the local depth of the fluid in said conduit;
and(d) multiplying said selected flow coefficient (CF) with said sensed velocity signal (VS) thereby to produce a crossed-sectional average velocity (V ). - The method as defined in claim 11, further comprising the steps of:(e) producing a pipe size signal (PS) indicating the size of the conduit;(f) multiplying said sensed depth signal (DS) by said pipe size signal (PS) thereby, to produce an area signal (AS); and(g) multiplying said area signal by said cross-sectional average velocity signal to produce a flow signal (QS) indicating the rate of fluid flow in said open-channel conduit.
- The method as defined in claim 12 further including the steps of:(h) storing a plurality of sets of data including reference velocity (VR) reference depth (DR), pipe size (PS), sensor type (ST) and the ratio of cross-sectional average velocity to reference velocity corresponding with the different site condition, respectively.
- The method as defined in claim 13 further including the steps of:(i) storing a plurality of reference depth to reference velocity ratios corresponding to different site conditions;(j) dividing the site depth signal by the site velocity signal to produce a site ratio signal;(k) comparing said site ratio signal with said stored reference ratio signals;(1) selecting a flow coefficient (CF) corresponding to the reference ratio that most nearly corresponds with said site ratio; and(m) multiplying the measured velocity signal by said selected flow coefficient (CF).
- The method as defined in claim 12, further comprising:(h) generating a plurality of sets of reference depth (DR) signals corresponding to a plurality of flow signals (QS) each of which is representative for one of various flow rates at a specific site, respectively;(i) storing said set of reference depth and flow signals in a signal memory means;(j) measuring the depth (DS) at a specific site location; and(k) comparing said sensed depth (DS) with said stored depth (DR) select a corresponding flow signal (QS).
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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US517214 | 1995-08-21 | ||
US08/517,214 US5684250A (en) | 1995-08-21 | 1995-08-21 | Self-calibrating open-channel flowmeter |
PCT/US1996/013291 WO1997008515A2 (en) | 1995-08-21 | 1996-08-21 | Self-calibrating open-channel flowmeter |
Publications (3)
Publication Number | Publication Date |
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EP0792441A2 EP0792441A2 (en) | 1997-09-03 |
EP0792441A4 EP0792441A4 (en) | 1998-11-11 |
EP0792441B1 true EP0792441B1 (en) | 2003-10-22 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP96928890A Expired - Lifetime EP0792441B1 (en) | 1995-08-21 | 1996-08-21 | Self-calibrating open-channel flowmeter |
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US (1) | US5684250A (en) |
EP (1) | EP0792441B1 (en) |
JP (1) | JP3202992B2 (en) |
AU (1) | AU6848096A (en) |
DE (1) | DE69630437T2 (en) |
WO (1) | WO1997008515A2 (en) |
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Publication number | Priority date | Publication date | Assignee | Title |
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US5808195A (en) * | 1997-05-21 | 1998-09-15 | Ads Environmental Services | Arrangement for determining liquid velocity versus depth utilizing historical data |
AU5039399A (en) * | 1998-07-03 | 2000-01-24 | Neles Field Controls Oy | Method and arrangement for measuring fluid |
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- 1996-08-21 WO PCT/US1996/013291 patent/WO1997008515A2/en active IP Right Grant
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- 1996-08-21 DE DE69630437T patent/DE69630437T2/en not_active Expired - Lifetime
- 1996-08-21 EP EP96928890A patent/EP0792441B1/en not_active Expired - Lifetime
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DE69630437D1 (en) | 2003-11-27 |
WO1997008515A3 (en) | 1997-05-22 |
US5684250A (en) | 1997-11-04 |
JP3202992B2 (en) | 2001-08-27 |
JPH10508112A (en) | 1998-08-04 |
EP0792441A4 (en) | 1998-11-11 |
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